A Local Area Network (LAN) is a collaborative environment including interconnected network nodes, which share services and exchange information. LAN technologies, such as Ethernet technologies, specified in the IEEE 802 standard, enable the interconnection of network nodes within a limited distance typically spanning a building. Ethernet technologies enjoy a very wide use and therefore are supported on a very large portion of installed communications infrastructure. Typically the information is conveyed in accordance with the Internet Protocol (IP), which is widely accepted as a LAN Layer3 (L-3) protocol.
As many enterprises (government organizations, companies, etc) grew beyond what can be housed in a single building, the need to share services and information freely between multiple sites evolved accordingly. These sites may be distributed over many sites either in a city, in a country, or internationally. Thus, the need to connect the site LANs, or LAN segments shared by the same user resulted in the development of the emulated LAN (ELAN) technologies. While the LAN segments of an emulated LAN generally use the same communication protocol, which may use a different communication protocol. A service provider must operate the emulated LANs for a certain customer seamlessly, as if they were one customer network (a virtual LAN.
Service provider networks typically manage regional public communications networks generally referred to as Metropolitan Area Networks (MANs), to which customer LANs connect. At a higher interconnection level, interconnectivity is provided between service provider communications network MANs via carrier communications networks, the combination forming what are known as Wide Area Networks (WANs). The Internet is a public conglomeration of WANs.
Most service provider communications networks operate in accordance with the IP protocol because of the wide utilization of the IP protocol in customer LANs. However, service provider networks may use various technologies such as SONET, ATM, Frame Relay, IP and interfaces that are provided to the respective LANs. Virtual LAN (VLAN) technologies extend the IEEE 802 standard specification to address customer traffic differentiation in a MAN/WAN environment to provide free exchange of information between LAN segments at different customer sites within a protected emulated LAN context. Providing VLAN support is the most complex and challenging of all Ethernet based services.
VLAN technologies as defined in IEEE 802.1q require the use of a unique global VLAN identifier (VLAN ID) for each customer. The VLAN ID is to be used globally to tag exchanged information within confines of the customer's emulated LAN context, when conveyed in the service provider's communications network and/or the carrier's communications network. According to this standard, different customer LAN segments associated with the same VLAN and connected to different parts of service providers communications networks from corresponding sites, share a common globally unique VLAN ID. Depending on the implementation, Customer Located Equipment (CLE) providing connectivity between customer LANs, service provider communications network nodes, and/or carrier communications network nodes need to be configured with globally unique VLAN IDs. As multiple entities, such as different customer sites, multiple service providers, and multiple carriers need to differentiate the customer traffic, the limited VLAN ID space available must be carefully managed overall. This introduces a large management overhead as the IEEE 802.1q standard specification only provides for about 4000 useful VLAN IDs and is therefore capable to support only up to 4000 emulated LANs.
Solutions providing central management of the limited VLAN ID space have been proposed and implemented, however these are not satisfactory as the entity providing the central VLAN ID space management does not necessarily have a direct relationship with each customer. Today, emulated LAN services have to be manually provisioned which is time consuming, error prone, and requires coordination of efforts involving multiple entities to ensure the VLAN IDs are unique throughout.
The parent US Patent Application identified above provides a method of provisioning virtual private LAN services, also known as VPNS, that uses tunneling technologies via virtual connections established between Provider Edge equipment (PEs), and learning bridge functionality at Customer Located Equipment (CLE). To summarize, the customer located equipment performs the learning bridge functions, including MAC address learning and flooding, while the provider equipment connected on the service provider network performs tunneling. This separation of functionality results in a less restrictive use of VLAN IDs, which need only to be unique in the access network portion of the service provider's network. Other advantages of this separation are that the PEs are not burdened with the bridging function, unique global VLAN IDs are not required, and the solution is simple, scalable and oriented to a leased line business model/operation.
On the other hand, adoption of the VPN approach in the parent U.S. Patent Application raises new issues that need to be addressed, notably hub redundancy, meaningful site to site service level agreements (SLA) and interconnection of sites with different access media.
In order to be successful, data communication service providers and/or operators need to offer emulated LAN services, which work at least as well as what customers themselves can provision. Thus, there is a need for a service provider/operator to provision emulated LAN services with high resiliency at low cost, enabling faster connectivity recovery than allowed by the existing services.
There have been previous attempts to provide SLA site-to-site in an emulated LAN context. However, it was thought that the provider edge equipment would need to filter or rate-limit the traffic based on the destination MAC address of the service. This is not a simple problem, as it requires the provider edge equipment to keep track of the MAC addresses of the frames going to different sites. More particularly, it is not known a priori how much bandwidth is required from an end customer site to other sites.
Existing solutions only allow emulated LAN services to be offered in a hose model, whereby the provider polices the ingress bandwidth of a customer UNI to an emulated LAN service. Since all that is known is the amount of bandwidth a site can send to the emulated LAN, this model does not allow a provider to provision the network for this service.
There is a need for a service provider to offer emulated LAN services with specified SLA site-to-site or UNI to UNI SLA.
Still further, there is a need for network provider/operator to provision emulated LAN services for sites with different access media.